Have come across a 16A Ring Final

[littlespark]

As far as the OP question, we dont know if there's info regarding why its been downrated.
Either there is a break in the ring somewhere, and its been converted to 2x radials, or part of the ring has been wired in 1.5 or something, which means a 32A cannot be used.

Sorry..."bypassing" wasn't the right choice of word.

 

[Risteard]

Quite common to find ring final circuits on 20A protective devices here. I must admit, it drives me nuts. Why go to the effort of installing and verifying a ring final circuit only to remove its primary benefit?

 

[Julie.]

bloody hell.no wonder females have frizzy hair and fried brains.

Hey!!!

I object to that, I haven't got frizzy hair!

 

[Zlodej]

I admit that I am one of those people who fit them.
Among reasons is when wiring bedrooms with a view to alterations latter for example when there was a possibility of house being latter converted to HMO or case when we were not sure if Gas arrives and as such giving excess number of rings for potential heaters. I am of a believe that if you can make something more safe then do so and where usage is expected to be low enough for B20. I would use B20 MCB providing protection and reacting under fault condition even when current enough to blow B32. Next point is that if you lose one of the cable contacts on a ring (break the ring) and your current flows via only one cable, It limits flow.
So I disagree with a term" "upgrade" to 32.
I fit smoke alarms on B3 MCB's.
I have also previously UPGRADED ring circuit MCB from B32 to more sensitive B16 on an ocasion when older wirings Zs was too high, but insulation test was still above 120M.
NOTE: As I have previously been refered to as possible troll for being one of those people against Rings I did made an attempt to avoid criticising them in this message to avoid flame (spark)

 

[Zlodej]

Quite common to find ring final circuits on 20A protective devices here. I must admit, it drives me nuts. Why go to the effort of installing and verifying a ring final circuit only to remove its primary benefit?

I would chanlenge you on that As many consider primary benefit of RFC to be secondary earthing (or connection route) should the cable gets disconnection or damage along the route.
While I am not a fan of RFC myself another of the benefits greater then its maximum fuse size is that in the event of lose or limited connection the other leg will have lower resistance and as such the resulted arcing is likely to be far lower to none, where on radial where there is no parallel path all current would have have to flow through it.

 

[Mikegh]

I would chanlenge you on that As many consider primary benefit of RFC to be secondary earthing (or connection route) should the cable gets disconnection or damage along the route.
While I am not a fan of RFC myself another of the benefits greater then its maximum fuse size is that in the event of lose or limited connection the other leg will have lower resistance and as such the resulted arcing is likely to be far lower to none, where on radial where there is no parallel path all current would have have to flow through it.

Dunno

Id say its hard to argue that capacity is the main benefit

'Secondary earthing' , lower efli and volt drop would be Secondary benefits I reckon

 

[Dustydazzler]

I always thought the old 32a RFC was to save cable and so that an entire houses sockets could be wired in 1 big circuit.
This was when you probably only had 7 maybe 8 sockets in an entire 3 bedroom property.
Many old houses you work on often still have the old 3036 board with just 3 circuits , Lights , Ring and Cooker

 

[Mikegh]

I always thought the old 32a RFC was to save cable and so that an entire houses sockets could be wired in 1 big circuit.
This was when you probably only had 7 maybe 8 sockets in an entire 3 bedroom property.
Many old houses you work on often still have the old 3036 board with just 3 circuits , Lights , Ring and Cooker

They'd be related wouldn't they

Material costs and capacity

2 sides of the same coin I reckon

 

[Intoelectrics]

Hey!!!

I object to that, I haven't got frizzy hair!

I've got no hair, however my brain is fried!

 

[telectrix]

I've got no hair, however my brain is fried!

sure you not going through a sex change?

 

[Intoelectrics]

sure you not going through a sex change?

Who knows, these days with all the gender identities I'm not sure.

 

[EricMark]

There are two limits to length of cable in ring finals, one is enough current should be able to flow to operate the magnetic part of the MCB/RCBO and the other is the voltage should not drop below the limits.

The latter is rather hit and miss, there is no hard and fast rules, we are told it is worked out as 20 amp in centre as 12 amp even spread, so 26 amp is used to calculate cable length and with 2.5 mm that works out at 106 meters.

But with a large home, by dropping to 16 amp you can have 180 meters of cable, personally would look at lollipop idea and use even 10 mm if required to a twin cooker outlet plate and form the ring final from that. But there is no hard and fast rules, I have in the past used 6 mm to junction boxes and spurs to each socket in a warehouse where the 24 foot drops from false ceiling in the refrigerated room would have cause problems with volt drop for the cleaning equipment to be used in the cheese store.

Although designed for homes, ring finals are used elsewhere, but in the home the advantage is reduction of cable used, and number of RCBO's required to allow many sockets which can have the 3 kW load without causing it to trip.

In the main swapping to less than 32 amp is because of an error somewhere.

 

[SparkySy]

Has the circuit been down rated due to the installation of the cable running through thermal insulation? I've seen a couple like this where a large amount of cellotex insulation was used!
Sy